Recoding based on the value of next case

[devoidx]

Hey all, I'd like to recode a variable's value (lets say Variable A) from 0 to 1 if the next case also has a value of 1 for variable A...so ideally kinda like:

DO IF (A = 1).
RECODE lag(A) (0=1).
END IF.
EXECUTE.

obviously this doesn't work but explains what I'd like to do...any ideas?
thanks.

[Bruce Weaver]

How about this?

DO IF (A EQ 1) and ($Casenum GT 1).
- IF LAG(A) EQ 0 LAG(A) = 1.
END IF.

devoidx wrote

Hey all, I'd like to recode a variable's value (lets say Variable A) from 0 to 1 if the next case also has a value of 1 for variable A...so ideally kinda like:

DO IF (A = 1).
RECODE lag(A) (0=1).
END IF.
EXECUTE.

obviously this doesn't work but explains what I'd like to do...any ideas?
thanks.

[devoidx]

Bruce Weaver wrote

How about this?

DO IF (A EQ 1) and ($Casenum GT 1).
- IF LAG(A) EQ 0 LAG(A) = 1.
END IF.

Thanks , tried it but getting the error: "The function appearing on the left side of the assignment operator (equals sign) is not valid in that context."

[Bruce Weaver]

Yes, of course.  What was I thinking?  You may need to sort the file first, like this:

COMPUTE CaseNum = $Casenumber.
*EXECUTE. /* May be needed--can't test right now.
SORT CASES by CaseNum (D).
DO IF LAG(A) EQ 1.
- RECODE A (0=1).
END IF.
EXECUTE.
SORT CASES BY CaseNum(A).
 
Does this work as expected?  (No SPSS at home, so I can't test right now.)

devoidx wrote

Bruce Weaver wrote

How about this?

DO IF (A EQ 1) and ($Casenum GT 1).
- IF LAG(A) EQ 0 LAG(A) = 1.
END IF.

Thanks , tried it but getting the error: "The function appearing on the left side of the assignment operator (equals sign) is not valid in that context."

[Rich Ulrich]

The old solution for "next record" was to sort the file into reversed order
and use LAG( ).  I notice that this solution would produce a "1" in every
record after the first occurrence of "1" (in the reversed file).  If that is what
you want - an iterated use of "1" to mark those records - then you could do that.

Here is a procedure without that problem/feature; a program that does not
get much use.   Pick up the next value of A with the program call,

SHIFT VALUES var=A  result= NextA  Lead=1.

Then do what computation you want.  I do notice, that if you run the thing
more than once -- using the simple description that you gave -- you will
get "1" promulgated to a record earlier each time.   SO -- That sort of
file-changing is *terrible*, in principle.  If faced with that circumstance, I
would use a new variable, "NewA", which is assigned the revised value; and
remember to use it instead using the Old A.  Maybe, rename the old A to BadA,
to make sure that it doesn't sneak itself into any future analyses.

--
Rich Ulrich

> Date: Tue, 24 Nov 2015 15:08:46 -0700

> From: [hidden email]
> Subject: Recoding based on the value of next case
> To: [hidden email]
>
> Hey all, I'd like to recode a variable's value (lets say Variable A) from 0
> to 1 if the next case also has a value of 1 for variable A...so ideally
> kinda like:
>
> DO IF (A = 1).
> RECODE lag(A) (0=1).
> END IF.
> EXECUTE.
>
> obviously this doesn't work but explains what I'd like to do...any ideas?
> thanks.
>

===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD

[devoidx]

Yeah using sort to flip the cases and putting the next case, before would work...I was crossing my fingers for a way that i wouldn't need to change my sort order as it is already sorted in a particular way (based on 3 other variables) and it needs to maintain that order. Thanks though! =]

Bruce Weaver wrote

Yes, of course.  What was I thinking?  You may need to sort the file first, like this:

COMPUTE CaseNum = $Casenumber.
*EXECUTE. /* May be needed--can't test right now.
SORT CASES by CaseNum (D).
DO IF LAG(A) EQ 1.
- RECODE A (0=1).
END IF.
EXECUTE.
SORT CASES BY CaseNum(A).
 
Does this work as expected?  (No SPSS at home, so I can't test right now.)

devoidx wrote

Bruce Weaver wrote

How about this?

DO IF (A EQ 1) and ($Casenum GT 1).
- IF LAG(A) EQ 0 LAG(A) = 1.
END IF.

Thanks , tried it but getting the error: "The function appearing on the left side of the assignment operator (equals sign) is not valid in that context."

[Bruce Weaver]

You're right, Rich.  SHIFT VALUES looks like the way to go.

Rich Ulrich wrote

The old solution for "next record" was to sort the file into reversed order
and use LAG( ).  I notice that this solution would produce a "1" in every
record after the first occurrence of "1" (in the reversed file).  If that is what
you want - an iterated use of "1" to mark those records - then you could do that.

Here is a procedure without that problem/feature; a program that does not
get much use.   Pick up the next value of A with the program call,

SHIFT VALUES var=A  result= NextA  Lead=1.

Then do what computation you want.  I do notice, that if you run the thing
more than once -- using the simple description that you gave -- you will
get "1" promulgated to a record earlier each time.   SO -- That sort of
file-changing is *terrible*, in principle.  If faced with that circumstance, I
would use a new variable, "NewA", which is assigned the revised value; and
remember to use it instead using the Old A.  Maybe, rename the old A to BadA,
to make sure that it doesn't sneak itself into any future analyses.

--
Rich Ulrich

> Date: Tue, 24 Nov 2015 15:08:46 -0700
> From: [hidden email]
> Subject: Recoding based on the value of next case
> To: [hidden email]
>
> Hey all, I'd like to recode a variable's value (lets say Variable A) from 0
> to 1 if the next case also has a value of 1 for variable A...so ideally
> kinda like:
>
> DO IF (A = 1).
> RECODE lag(A) (0=1).
> END IF.
> EXECUTE.
>
> obviously this doesn't work but explains what I'd like to do...any ideas?
> thanks.
>
     
=====================
To manage your subscription to SPSSX-L, send a message to
[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command
SIGNOFF SPSSX-L
For a list of commands to manage subscriptions, send the command
INFO REFCARD

[devoidx]

thanks guys, i'll play around with SHIFT VALUES and report back!

Rich Ulrich wrote

The old solution for "next record" was to sort the file into reversed order
and use LAG( ).  I notice that this solution would produce a "1" in every
record after the first occurrence of "1" (in the reversed file).  If that is what
you want - an iterated use of "1" to mark those records - then you could do that.

Here is a procedure without that problem/feature; a program that does not
get much use.   Pick up the next value of A with the program call,

SHIFT VALUES var=A  result= NextA  Lead=1.

Then do what computation you want.  I do notice, that if you run the thing
more than once -- using the simple description that you gave -- you will
get "1" promulgated to a record earlier each time.   SO -- That sort of
file-changing is *terrible*, in principle.  If faced with that circumstance, I
would use a new variable, "NewA", which is assigned the revised value; and
remember to use it instead using the Old A.  Maybe, rename the old A to BadA,
to make sure that it doesn't sneak itself into any future analyses.

--
Rich Ulrich

> Date: Tue, 24 Nov 2015 15:08:46 -0700
> From: [hidden email]
> Subject: Recoding based on the value of next case
> To: [hidden email]
>
> Hey all, I'd like to recode a variable's value (lets say Variable A) from 0
> to 1 if the next case also has a value of 1 for variable A...so ideally
> kinda like:
>
> DO IF (A = 1).
> RECODE lag(A) (0=1).
> END IF.
> EXECUTE.
>
> obviously this doesn't work but explains what I'd like to do...any ideas?
> thanks.
>
     
=====================
To manage your subscription to SPSSX-L, send a message to
[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command
SIGNOFF SPSSX-L
For a list of commands to manage subscriptions, send the command
INFO REFCARD

[Kirill Orlov]

Lag() isn't allowed on the left hand side.
Lead function is available not as a transformation function but as a Create Time Series procedure (see in Tranform menu).
Shift Values is also an option.
And, of course, MATRIX is our lifesaver forever.

25.11.2015 2:35, devoidx пишет:

Bruce Weaver wrote

How about this?

DO IF (A EQ 1) and ($Casenum GT 1).
- IF LAG(A) EQ 0 LAG(A) = 1.
END IF.

===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD

[devoidx]

SHIFT VALUES took care of my problem like a champ! thanks for the suggestion!

[Bruce Weaver]

How about posting the final solution then, so that folks searching the archives in the future can see it?  ;-)

devoidx wrote

SHIFT VALUES took care of my problem like a champ! thanks for the suggestion!

[devoidx]

Sure, it's pretty much identical to what Rich suggested though so:

I created newA which is the exact copy of originalA variable and:
SHIFT VALUES variable=originalA  result= NextA  Lead=1.
DO IF (NextA = 1).
RECODE newA (0=1).
END IF.

Bruce Weaver wrote

How about posting the final solution then, so that folks searching the archives in the future can see it?  ;-)